Five people have re-painted over a "heartbreaking" vandalised unofficial memorial to a drowned Welsh village.
The wall's slogan "Cofiwch Dryweryn" - Remember Tryweryn - was vandalised to read "Elvis" recently.
The original graffiti appeared near Aberystwyth, after the village of Capel Celyn in Gwynedd was flooded in 1965.
Elfed Wyn Jones, who helped carry out the re-painting, said: "We had to do something - it is a staple of Welsh history."
The 21-year-old, from Aberystwyth, said it was "heartbreaking" to see the vandalism on the wall.
"We decided we needed to set an example by doing it quickly. It is a memorial to a tragedy in Welsh history," he added.
Mr Wyn Jones and his four friends began painting at 21:00 GMT on Sunday and slept in their cars until the paint dried at 04:00 the next day.
They returned to the wall on Monday to daub the original "Cofiwch Dryweryn" slogan back on.
Plaid Cymru Welsh AM Bethan Sayed said the re-painting "shows how people have that energy to go and make change again".
She told BBC Radio Wales' Good Morning Wales programme: "I think it is important that we do respect it.
"It is integral to our history as a Welsh people."
Mrs Sayed had called for the Welsh Government to protect the site, like the Banksy mural in Port Talbot.
"Perhaps we could make a site of historical importance out of the 'Cofiwch Dryweryn' art," she said.
A Welsh Government spokesperson said it "would be willing to engage in talks with the Llanrhystud Community Council and interested parties on better interpretation and protection of the site".
"The 'Cofiwch Dryweryn' memorial is not a listed structure, although Cadw is always prepared to reconsider a request for listing if there is new evidence," it added.
"Previous discussions about its future have questioned whether listing would be the best way of providing the protection it needs; however, we would like to explore options for the future."
Liz Saville Roberts, Plaid Cymru MP for Dwyfor Meirionnydd, said the wall was a "symbolic and poignant reminder" of why Welsh culture and communities "cannot be allowed to be so drastically undervalued ever again".
"This act of mindless vandalism is deplorable and shows complete disregard and ignorance of the significant development in Wales' national consciousness following the flooding of Capel Celyn."
The original graffiti came about as a response to Capel Celyn being flooded to give Liverpool water, which sparked protests and was widely seen as igniting the Welsh nationalist and language movement.
The wall on the main road from Aberystwyth to Llanrhystud has been defaced several times in the past.
In 2005, Liverpool City Council issued an apology over Tryweryn for "any insensitivity shown" by the previous council's endorsement of the proposal to flood the valley.